A precision time protocol IEEE 1588v2 defines a time synchronization technology based on data packet transmission. The technology adopts a timestamp mechanism and a master-slave clock solution to encode time for transmission, and meanwhile, utilizes symmetry of network links and delay measurement technologies to implement synchronization of a frequency and time of master and slave clocks.
The IEEE 1588v2 requires optical fibers for transmitting and receiving signals to be strictly symmetric, that is, an optical fiber transmission delay d1 from a master device to a slave device needs to be equal to an optical fiber transmission delay d2 from the slave device to the master device. If d1 is not equal to d2, an error is caused.
In the prior art, in order to improve time synchronization precision of an asymmetric network, a commonly-adopted method is that, at the time of deployment, acceptance and change of a network structure, manually performing a time synchronization compensation operation, which includes: manually measuring a transmission delay of each pair of optical fibers one by one by utilizing a delay measurement device such as an optical time domain reflectometer (OTDR) or an optical frequency domain reflectometer (OFDR), and then manually inputting measured transmission delay data into a time synchronization device, thereby implementing time synchronization compensation.